/Engine/Plugins/Runtime/MeshModelingToolset/Source/MeshModelingTools/Public/ToolActivities/PolyEditInsertEdgeActivity.h
Update the preview unless we've already computed one with the same parameters (such as when snapping to the same vertex despite moving the mouse).
void ConditionallyUpdatePreview ( const [FGroupEdgeInserter::FGroupEdgeSplitPoint](API\Plugins\DynamicMesh\Operations\FGroupEdgeInserter\FGroupEdgeSplitPoint) & NewEndPoint, int32 NewEndTopologyID, bool bNewEndIsCorner, int32 NewCommonGroupID, int32 NewBoundaryIndex )